Hydrogen silesquioxane (HSQ) is an inorganic compound having the chemical formula [HSiO3/2]n. An example HSQ includes the cubic cluster H8Si8O12. HSQ can be used as a resist in optical lithography (e.g., extreme ultraviolet (EUV) and electron-beam (e.g., e-beam) lithography) to achieve fine resolution. For example, HSQ is sensitive to e-beam or EUV lithography, which is used for advanced nodes. HSQ can also be used as a material for dummy gates in a replacement gate flow to fabricate metal oxide semiconductor field-effect transistors (MOSFETs).
A MOSFET is a type of field-effect transistor (FET) that has an insulated gate, the voltage of which determines a conductivity of the device. A MOSFET's ability to change conductivity based on the amount of applied voltage is utilized for amplifying or switching electronic signals.